feat: encapsulate identity with better-auth

modules/identity/services/session.ts

@@ -0,0 +1,34 @@
+import cookie from "cookie";
+
+import { config } from "../config.ts";
+import { auth } from "./auth.ts";
+
+/**
+ * Get session headers which can be applied on a Response object to apply
+ * an authenticated session to the respondent.
+ *
+ * @param accessToken - Token to apply to the cookie.
+ * @param maxAge      - Max age of the token.
+ */
+export async function getSessionHeaders(accessToken: string, maxAge: number): Promise<Headers> {
+  return new Headers({
+    "set-cookie": cookie.serialize(
+      "better-auth.session_token",
+      encodeURIComponent(accessToken), // URL-encode the token
+      config.cookie(maxAge),
+    ),
+  });
+}
+
+/**
+ * Get session container from request headers.
+ *
+ * @param headers - Request headers to extract session from.
+ */
+export async function getSessionByRequestHeader(headers: Headers) {
+  const response = await auth.api.getSession({ headers });
+  if (response === null) {
+    return undefined;
+  }
+  return response.session;
+}